Originální popis anglicky: 
sys/times.h - file access and modification times structure
Návod, kniha: POSIX Programmer's Manual
#include <sys/times.h>
The 
<sys/times.h> header shall define the structure 
tms,
  which is returned by 
times() and includes at least the following
  members:
 
clock_t  tms_utime  User CPU time. 
clock_t  tms_stime  System CPU time. 
clock_t  tms_cutime User CPU time of terminated child processes. 
clock_t  tms_cstime System CPU time of terminated child processes. 
 
The 
clock_t type shall be defined as described in
  
<sys/types.h> .
The following shall be declared as a function and may also be defined as a
  macro. A function prototype shall be provided.
 
clock_t times(struct tms *);
 
The following sections are informative.
None.
None.
None.
<sys/types.h> , the System Interfaces volume of
  IEEE Std 1003.1-2001, 
times()
Portions of this text are reprinted and reproduced in electronic form from IEEE
  Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
  Operating System Interface (POSIX), The Open Group Base Specifications Issue
  6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
  Engineers, Inc and The Open Group. In the event of any discrepancy between
  this version and the original IEEE and The Open Group Standard, the original
  IEEE and The Open Group Standard is the referee document. The original
  Standard can be obtained online at http://www.opengroup.org/unix/online.html
  .